Nowadays, with striking popularization of digital cameras, the chances of handling digital images are increasing at home and businesses alike. Based on this, it is demanded to improve the functions of application software aiming at retouching images (e.g., to change a digital image to a favorite tint). To meet such user's demand, developers are now developing various kinds of software with various functions.
In such software, as a general user interface used to change the color of a digital image, a GUI (Graphical User Interface) which categorizes change items into three elements, i.e., hue, chroma, and brightness, and allows the user to change respective items is known (e.g., see Japanese Patent Laid-Open No. 08-186727).
The user changes the values of the respective elements by, e.g., moving slider bars which are movable to the right and left, or by inputting numerical values of hue, chroma, and brightness. In order to confirm the degree of a change in color, the following method is used. That is, a digital image to which the change is immediately applied is displayed, so that digital images with the original and destination colors are displayed side by side on the screen, and the color selected by the user is changed to a favorite color on a dedicated color palette.
However, the conventional user interface has a configuration for independently changing three elements, i.e., hue, chroma, and brightness. For example, when a color is to be changed, slider bars equipped for these three elements must be moved. For this reason, it is difficult for the user to recognize information about the relevance of the three elements and a changeable color range, and a long time is required to find out a desired color. It is also difficult to visually recognize the relationship between the original and destination colors on the color space. Conventionally, some interfaces display one of the original and destination colors on a chromaticity diagram, but no interfaces that simultaneously display the original and destination colors are available.